I also think that 10.10 was one of the best refined ubuntu releases but I cannot stick to such old software (apps). I cannot add a ppa for each application I use and most of my everyday applications (netbeans, gimp, inkscape, libreoffice, firefox etc) have grown by leaps and bounds since 2010

As for securiy I don't think there should be a problem unless you host a public web (or other) server.